1. Field of the Invention
The present invention relates to a drive apparatus, a control method for the drive apparatus, a storage medium in which is stored a program controlling the drive apparatus, and a power output apparatus.
2. Description of the Prior Art
Heretofore, an apparatus has been proposed for this type of power output apparatus comprising a capacitor that is connected to a positive bus line and a negative bus line of an inverter circuit for applying a three-phase alternating current to a motor, and a DC/DC converter capable of performing DC/DC conversion on the power from the DC power source and supplying to the capacitor. In this power output apparatus, a charge is stored into the capacitor by using a reactor for temporarily storing the current of the DC power source as energy and stepping up the voltage of the DC power source, and the motor is driven with this charged capacitor as a DC power source. The voltage step-up operation by the DC/DC converter is fixed at a switching frequency (carrier frequency) where the efficiency is considered suitable at a given operating point, and is performed by controlling the switching at this fixed switching frequency.
However, in this sort of power output apparatus, there is a problem in some instances where the DC/DC converter is not necessarily driven at an optimum switching frequency and the energy efficiency drops. The DC/DC converter operates according to the output (output requirement) required by the power output apparatus, and the point of the switching frequency where the efficiency is suitable also varies depending on the output requirement. Therefore, when driving the DC/DC converter at a fixed switching frequency, there are instances where the operation occurred at a poor efficiency point depending on the output requirement of the apparatus. The drop in energy efficiency of the DC/DC converter causes a drop in the energy efficiency of the overall apparatus.